Update Nichesphere installation to use GitHub repo

Author: jsnagai

.github/workflows/python-package.yml

@@ -29,7 +29,7 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         python -m pip install flake8 pytest
-        python -m pip install nichesphere
+        python -m pip install git+https://github.com/jsnagai/Nichesphere/
         python -m pip install pycrosstalker
         
         if [ -f requirements.txt ]; then pip install -r requirements.txt; fi